The newest packaged build can always be downloaded from the OpenRA website.
If you want to know what's happening on the absolute bleeding edge, read the history of /next on GitHub here: http://github.com/OpenRA/OpenRA/commits/next. This will become the next release, assuming it mostly works.

20110511

Engine:

Fix hotkeys firing on both key down and key up

Allow C4 delay to be configurable

Text field support for home and end keys

Fix world actor being owned by Creeps player (causing Neutral to be hostile) on new maps

Include gpu vendor string in graphics.log for unsupported cards

Fix crash with some aud files

Fix a rare crash when a repairing building is killed

Improvements to HackyAI

Generalize capture logic to work for any actor types

Support RA2-style missile trails

Fix helicopters failing to attack targets in some situations

Fix 'exploit detected' when using hotkeys on another players units

Relinquish spawn point in the game lobby when entering a spectator slot

Fix maps with >8 spawnpoints in the game lobby

Yaml loader crashes correctly when trying to inherit from a nonexistant actor

Bugs:
- Fix crash when hosting a second game.
- Fixed exploit where you could place a building anywhere.
- Fix aircraft, infantry becoming invincible in some circumstances.
- Fix a common aircraft desync.
- Unmuted the shellmap; it's now at 25% volume.